The processing of photographic materials such as films and printing papers (hereinafter referred to as films) in a photographic processor generally consists of development, fixation, washing and drying steps. The films that are fed into the processor are successively subjected to these steps.
The developing solution and fixing solution consumed in the development and fixation steps of the film processing, respectively, must be compensated by the necessary amount (this compensation is hereinafter referred to as the "replenishment" of the developing or fixing solution). Even if no film is processed, the activity of a certain developing solution, for example, a lith developer, is greatly reduced during storage and so must be replenished by an additional supply of a developing solution.
The first type of replenishment described above is usually referred to as replenishment after fatigue from processing (or simply "processing-exhaustion replenishment"). The second type of replenishment described above is referred to as replenishment time lapse exhaustion fatigue (or simply "time lapse exhaustion replenishment").
If the processing-exhaustion or time lapse exhaustion replenishment is excessive, either the exposed film is developed with the unreplenished developer or another corrective action, such as changing the replenishing ratio or stopping the time lapse exhaustion replenishment, must be taken. The above-described two types of replenishment and associated actions are effected in a processing solution activity control system. The present invention is directed to an improvement on this system, as well as a photographic processing apparatus that includes this system.
The system for controlling the activity of processing solutions is hereinafter described with particular reference to a lith developer. A schedule for the conventional method of replenishing a lith developer is shown in FIG. 1. In this method, two development replenishers (hereinafter referred to as replenishers), one for processing-exhaustion replenishment (hereinafter "RAB") and the other for time lapse exhaustion replenishment (hereinafter "RAC"), are supplied independently in such a manner that RAB is fed according to the amount of black area of the film being processed whereas RAC is first fed at the start of the processor's operation in an amount proportional to the number of hours spent before restarting the processor after its shutdown on the previous day, with a given amount of RAC supplied for every 1 or 2 hours of operation. In FIG. 1, A represents supplying RAB according to the amount of black area of the film being processed, B.sub.1 and B.sub.2 denote supplying RAC according to the number of hours spent before restarting the processor after its shutdown on the previous day (B.sub.1 : 14 hr, B.sub.2 : 15 hr), and C indicates supplying a given amount of RAC every 2 hours of the processor's operation. The formulation of RAB is primarily intended for correcting the sensitivity of the developer and RAC is so formulated as to correct the half-tone gradation.
However, in the method of FIG. 1, the activity of the developing solution varies with the processing conditions and other variables. This often results in inconsistent quality of the finished prints. To avoid this problem, the operator occasionally processes control strips and compares their densities with the reference conditions (the data for the fresh solution) to take any necessary action. The necessary actions are keyed to the specific troubles as shown in FIG. 2.
More specifically, the density on a predetermined position of a control strip is divided into four zones A, B, C and D according to how much it differs from the reference value (see FIG. 3), and the necessary action is taken for each zone.
(1) A-1 and A-2 zones: The activity of the developing solution is properly controlled and needs no adjustment.
(2) B-1 and B-2 zones: The developing solution is usable but its activity is not properly controlled and needs a remedial action for changing the replenishment ratio. Reduce the ratio if the zone is B-1 and increase it if the zone is B-2.
(3) C-1 and C-2 zones: The developing solution is unusable but its activity is still restorable by both temporary and sustained remedies.
C-1 zone: As the temporary remedy, develop a given volume of exposed film with unreplenished RAB for correcting the sensitivity. For correction of the half-tone gradation, stop the RAC replenishment. As the sustained remedy, decrease the replenishment ratio.
C-2 zone: As the temporary remedy, additionally supply RAB for correcting the sensitivity, and supply additional RAC for correcting the half-tone gradation. As the sustained remedy, increase the replenishment ratio for RAB and RAC.
(4) D-1 and D-2 zones: The developing solution is unusable and its activity is no longer restorable. Check the solution and the processor.
The operation manual available with each processor lists the specific number of exposed films to be developed with unreplenished developer, the amount of each replenisher to be supplied additionally and the degree of changing the replenishment ratio on the basis of a model processing by a model user. However, in actual cases, the processing conditions vary and a skilled operator must determine the specific value for each operation by experimentation. As shown in FIG. 3, the state of the developing solution is divided into four stages depending upon how much the density of the reference control strip differs from the fresh state, but the reliability of this strip has not been fully confirmed. Furthermore, the non-linearity of film processing makes the correcting conditions non-linear and no necessary adjustment to remove this non-linearity has been considered in the conventional system.